The present invention relates to an air trap for liquid circulation line. More particularly, it relates to an air trap for a liquid circulation line for circulating a liquid such as a coolant or the like, capable of trapping bubbles in the liquid circulating through the liquid circulation line to prevent the bubbles produced in the circulation line from entering into a circulating pump.
Generally, cooling fans have been used for cooling systems of CPUs in personal computers or the like. Alternatively, water-cooled cooling systems are partially used in personal computers or the like because of their higher heat efficiency.
In such personal computers, large-sized products or desktop type personal computers may be equipped with a circulating pump with a large capacity, and thus they have no trouble with the capacity of the pump. In contrast therewith, small-sized products such as, for example, notebook-size personal computers have limits in size and weight and thus it is obliged to use a circulating pump with a small capacity. However, such small sized water-cooling systems have difficulties in constant discharge rate of the pumps because of formation of bubbles in the circulation line. In order to ensure the constant discharge rate, it is required to provide any mechanism for removing such bubbles from the coolant. For this purpose, there have been used gravity type air traps as shown in FIG. 5 or filter type air traps as shown in FIG. 6. However, the gravity type air trap does not function well if a notebook-size personal computer equipped with such an air trap is used under the circumstances turned upside down. On the other hand, the filter type air trap of FIG. 6 has a problem in that the coolant in the circulation line decreases in quantity by evaporation during long use.
It is therefore an object of the present invention to provide an air trap for liquid circulation line, which is capable of stabilizing a discharge rate of a pump by trapping bubbles produced in a liquid circulating in a liquid circulation line to prevent the bubbles from entering into a pump.
The present inventors have intensively researched in order to achieve the above object, and found that by trapping bubbles generated in a coolant in a part of the circulation line, instead of removing therefrom, it is possible to keep an amount of the coolant in the circulation line constant as well as to prevent the bubbles from entering into the pump.
According to the present invention, there is provided an air trap for liquid circulation lines, comprising an air reservoir provided in a liquid circulation line, and a hydrophilic filter arranged in said air reservoir to separate an upstream of a flow path therein from a downstream side thereof, said filter having liquid-permeability and air bubble-impermeability. In that case, it is preferred to use a hydrophilic filter having pores which meet conditions defined by the following equation (1):
P less than 4h/dxe2x80x83xe2x80x83(1)
where P represents a gas pressure, d is a diameter of the pores of the filter, and h is a surface tension of the liquid.
The air reservoir is composed of an internal space of a container arranged in and spaced from a housing, which has at a proximal end thereof a liquid inlet for liquid from the liquid circulation line and at a distal end thereof a liquid outlet for liquid to the liquid circulation line, and communicated with the liquid inlet at a distal end thereof. The container is provided in its wall with at least one window to allow the internal space thereof to communicate with the outer space formed between the housing and the container. The container is provided at its wall with at least one filter so as to close the at least one window thereof with the filter.
Alternatively, the air reservoir may be composed of an internal space of a flat housing provided in opposite flat walls thereof with an inlet for a liquid from the liquid circulation line and an outlet for a liquid to the circulation line respectively. The housing is further provided in the interior thereof with a filter so that the internal space thereof is partitioned to two spaces, i.e., a liquid inlet side and a liquid outlet side.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention.